Screw-propeller



H. LEITNER.

SCREW PROPEI LER. APPLICATION FILED MAR. 25. l9l9.

1,328,005. Patented Jan. 13, 1920.

2 SHEETS-SHE-il' I.

H. LEITNER.

. SCREW PROPELLEB. APPLICATION FILED MAR- 25. m9

1,328,005 Patented Jan. 13, 1920.

2 SHEETS-SHEET 2.

Wz'inesses. frwezziaz'.

I w M di @MQW HENRY LEITNER, OF WESTMINSTER, LONDON, ENGLAND.

Specification of Letters Patent.

sonEw-rnoPELLER.

Patented Jan. 13, 1920.

Application filed March 25, 1919. Serial No, 285,051.

To all whom it me concern:

Be it. known t at I, HENRY LEITNER, a subject of the King of Great Britain, resid- 'ing at 3 Victoria street, Vestminster, London, England, have invented new and useful Improvements in SCI'QWrPI'OPGllGI'S, of

which the following is a specification.

My invention relates to screw propellers, chiefly designed for use with air-craft, and to that class of propeller in which the blades are hollow, and are made of sheet metal plates welded or otherwise suitably joined at the edges.

The object of my invention is to improve the construction of propellers of this type, and more particularly that part of the propeller comprising the hub and adjacent parts of the blades where the stress is greatest.

To this end, according to my invention, I make the blades of sheet-metal rolled, stamped, or otherwise shaped to the required thickness and form, the two faces of the said blades being formed from separate sheets, the edges of which are welded or otherwise suitably united. Withinthe outer sheath, and more particularly in that part surrounding the hub and adjacent thereto, I provide a sheet metal liner or lamina, or a number of sheet metal liners or laminae, stamped or otherwise formed from a blank to conform with the shape of the outer sheath. The outer sheath and liner or liners are secured to a hub comprising a central tube adapted to fit the driving shaft and provided with shaped end driving plates which may be wholly or approximately flat,- and are preferably partially circular in outline for a short distance only on each side of a givendiameter line. In two opposite di, rections, and approximately at right angles to this diameterline, the plates are formed with extensions or horns, which may either be fiat or shaped to the curve which is isuallyglven to a propeller blade Where it )OlIlS the central boss. These horns are of such a shape that their edges correspond with the edges of the stamped or shaped.

sheet metal forming the blades. The end plates may further and advantageously be provided with a shoulder, or bead on their edges, or with a bead ridge or groove on their inside faces, on which to rest the edges of the sheet metal forming the blades and the laminae. Such a construction enables the sheet metal to have a long solid edge to which it can be welded, and to be practically Without the filling-in pieces which would otherwise be required. Much greater strength is thus obtained at their junction with the hub. A propeller constructed in this manner could be driven at a moderate speed without any welding or other attachment of the plates to the hub. This of course is not advisable, but it serves to show the greatly improved construction whereby much of the strain is taken off the welded joints.

To increase the rigidity or stiffness of the blade internal ribs and transverse gage or distance pieces may be provided, the former being advantageously made. integral with the liners and the latter separate pieces suitably secured to the sheaths.

To enable my invention to be fully understood I will describe it by reference to the accompanying drawings, in which;

Figure 1 is an elevation of one form of propeller constructed according to my invention.

Fig. 2 is a sectional elevation, and

Fig. 3 is a sectional plan of the same.

Figs. 4, 5, 6 and 7 are respectively sec-- tions on the lines 4t, 5 5, 6-6 and 7-7, Fig. 1. I

Fig. 8 is a view of a detail'of the construction illustrated in Fig. 7. i

Fig. 9 is an elevation of theboss or hub ofthe propeller, and

Fig. 10 is a plan thereof. Figs. 11 and 12 areviews similar to Fig. 2, illustrating modifications-"J Fig. 13 is a section ontlie line 1313, Fig. 12, and

14 is a detail of the construction illustrated in Fig. 13.

Referring to Figs. 1 to 10, a is the outer sheath of the propeller and b the liners or laminae of different lengths fitting within the same and within one another, as shown clearly in Figs. 2 and 3. c is the central tubeof the boss or hub having the flanges or end plates d. In this form of propeller the sheath a and the laminae are shaped to fit between the'flanges (Z, the latter being rabbeted or recessed at d to receive them, as shown clearly in Fig. 4. The sheath a and laminae b are bent to the required form and welded or otherwise connected together at their edges as indicated in Fig. 6. The dotted lines at (P, Fig. 4 indicate grooves which may be provided for lightening the structure.

' edges of the sheath a and lar structure as above referred to.

6, e are the horns or extensions on the hub flanges (Z designed to fill the spaces formed between the edges of the sheath a and laminae b where they separate to pass around the hub on opposite sides, which spaces would ordinarily require to be filled ,by separate filling pieces. These horns are formed with beveled surfaces f to which the laminae are welded or otherwise attached, the said surface merging into the rabbets (1 9, Figs. 7 and 8, indicates one of the gage or distance pieces between the walls of the sheath a for stiffening or constructional purposes, and k, 'i are lugs formed thereon in pairs. The lugs h when bent at right angles to the body of the gage piece, as indicated by the dotted lines in Fig. 8, serving for attachment to the edges of the plates forming the sheath by welding or otherwise, while the lugs 71 can be also bent at right angles and attached to the sheath by spot weldin or passed through holes in the latter and riveted or welded as indicated. These gage pieces, either with or without the lugs, may be welded inside one blade of the sheath before the blades are put together, or they may be welded on to the ends of the laminae, or the end of a lamina may have an extended strip or strips to whicha gage piece or pieces is or are fixed.

Fig. 11 ShOWs a construction wherein the laminae or liners b, of which two pairs are shown, do not follow the contour of the sheath a, as in Fig. 2, but cross the hub in a more direct line, and form, as it were, ties between the two blades, and a kind of cellu- Their edges are preferably welded to the end plates or flanges of the hub where they cross the latter. In a further modification instead of bringing the laminae across the hub, the sheath a may be so arranged, and the laminae caused to follow the outer contour, but this is not so advantageous.

In the construction illustrated in Figs. 12, 13 and 14, a single pair of laminae is shown having ribs j formed or pressed in them to stifien them. The opposed ribs abut, as shown, and'may be welded or otherwise attached together.

number of horns of the improved hub will be correspondingly increased.

I do not limit myself to the particular shape or design of propellers as shown in the drawing nor to the arrangement of parts in the particular manner herein illustrated and described, since it is obvious that many variations and modifications may be used without departing from the scope of the in-' vention.

' Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. A screw propeller comprising hollow blades formed of a sheet metal sheath having gaps adjacent the hub in combination with a hub. composed of a central tube and end plates having horns forming power transmitting filling pieces for the gaps in the sheath adjacentto the hub, substantially as hereinbefore described.

2. A screw propeller comprising hollow blades formed of an outer sheet metal sheath having gaps adjacent the hub with an internal laminal strengthening adjacent to the hub in combination with a hub composed of a central tube and end plates having horns forming power transmitting filling pieces for the gaps in the sheath adjacent to the hub, substantially as described.

'3. A screw propeller comprising hollow blades formed of an outer sheet metal sheath having gaps adjacent to the hub, with an internal laminal strengthening adjacent to the hub and internal transverse strengthening members, in combination with a hub composed of a central tube and end plates having horns forming power transmitting filling pieces for the gaps 1n the sheaths adjacent to the hub, substantlally as hereinbefore described.

HENRY LEI'TNER. 

